Air conditioner



FIG. 1 is a right front perspective view of the ornamental design for an air conditioner according to the invention;

FIG. 2 is a front elevational view of the air conditioner of FIG. 1;

FIG. 3 is a right side elevational view of the air conditioner of FIG. 1, the left side of which is a mirror image thereof; and,

FIG. 4 is a top plan view of the air conditioner of FIG. 1.

The structures depicted by means of broken lines in the figures have been shown for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an air conditioner, as shown and described. 